1. Field of the Invention
The present invention relates to a low-temperature showcase. More specifically, the present invention relates to a low-temperature showcase wherein evaporators are installed in the vent ports located at both sides of a storage chamber, respectively associated therewith, and a blast fan which can rotate reversibly is installed in the air passage, and thereby the two evaporators are put in cooling operation alternatively.
2. Description of the Prior Art
The low-temperature showcases of this kind are disclosed, for example, in the Japanese Patent Application Laid-Open No. 47176/1982 laid open on Mar. 17, 1982, the Japanese Patent Application Laid-Open No. 178176 laid open on Oct. 19, 1983 or the like. In these prior arts, an air passage around a storage chamber is divided into two parts by a fan case, and a blast fan capable of blowing air in both directions of the air passage is installed on this fan case. Then, evaporators are installed respectively in the air passages of both sides of the blast fan and operations thereof are switched over alternatively in a manner that when one of the evaporators is put in cooling operation, the other evaporator is put in defrosting operation. When the evaporator is put in defrosting operation, a refrigerant of high temperature which has passed through a condenser is carried through this evaporator.
In the above-described prior art, each evaporator comprises an evaporating pipe for evaporating a reduced-pressure liquid refrigerant and a defrosting pipe for passing through the high-temperature refrigerant. When one of the evaporators is put in defrosting operation, this evaporator is heated wholly by the defrosting pipe, and therefore the temperature of the air which has passed through the evaporator during defrosting is high and thereby the air of high temperature becomes a load of refrigeration for the other evaporator in cooling operation. Consequently, a large cooling capacity of evaporator is required, and thereby not only energy consumption becomes larger, but also the cost becomes higher.